Infectious Bite (disease is microscopic offspring dinosaurs that swim in the blood, begin escaping through pores, and eventually tear the host apart)

Instead of teeth, has a rotary bladed mouth

Can split into subunits, like Voltron in reverse. Each subunit is a smaller version of the big dinosaur.

Immortal. Will resurrect 1 minute after its apparent death.

It's gaze can trap up to 1d4-1 (min 1) souls inside it's head, with a failed save. Victims will fall unconscious and soulless until the dinosaur's head is broken open. 50% chance that dinosaur's head is full of angry ghosts. Trapped victims are visible in the dinosaur's eyes, beating on the surface like a window.

Pillow-like consistency, immune to bludgeoning attacks. Docile temperment, and will seek to hug people (until attacked). People who are hugged for more than one round will be absorbed like an ooze. Dinosaur is also pink and has big, cute, and has big eyes.

Fractal genitalia. Save vs confusion for 1d6 rounds. Those who fail will be unable to figure out what gender a person is for another 1d6 days.

Covered in spines. Those attacking in melee take 1d6 damage. Can throw them like a wyvern.

Transformo-dinosaur. At will, or when at 50% health, can transform into:

Tank

Submarine

Jet

Another mutant dinosaur (roll a new mutant dinosaur!)

Vampiric. Coffin is not a coffin, but is instead the nearest volcano (if a fantasy game) or abandoned blast furnace (if game is gonzo or sci-fi). Drains heat instead of blood, leaving corpses that are permanently cold. Is burning hot to the touch, and will damage people if grappled.

Complications (50% that any given random encounter has a complication, slash DM judgement)

Is actually a transformed:

wizard

prince/princess

some stupid animal like a dog or iguana

Has a howdah on the back with a bunch of maggoty corpses, one of which is carrying a treasure map and mechanical parrot

Is escaped from the royal zoo, wears a collar, and is worth a fortune if returned

Is an agent of the dinosaur god, and has been punished with mutation for its sins.